JPS63239306A - Muffler made of heat resistant epoxy resin - Google Patents

Abstract

PURPOSE:To improve the noise damping efficiency of the muffler in the caption by obtaining a muffler body in a molding work of heat resistant epoxy resin obtained in the process of a predetermined heat treatment for a dense bridge formation, after adding curing agent and a king or more than two kinds of inorganic substance to the epoxy resin. CONSTITUTION:A muffler installed in the exhaust system of an internal combustion engine is fundamentally constituted with combined end plates 4 and 5 connected to the input and output pipes 2, 3 of exhaust gas on both ends of a muffler body 1 formed in a cylindrical or rectangular tube shape. The muffler body 1 and end plates 4 and 5 in this muffler is molded with heat resistant epoxy resin instead of a conventional steel plate or stainless steel. And the heat resistant epoxy resin to be used is of such a type in which curing agent and a kind or more than two kinds of inorganic substance is added to the epoxy resin and the predetermined heat treatment is made for a dense bridge formation, and which is changed over to the rubber region from the glass region via the viscoelastic region in a state at a constant high temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an exhaust muffler that is attached to an internal combustion engine of an automobile or the like and attenuates exhaust noise while passing exhaust gas generated by the engine. be.

Conventional Technology Generally speaking, if high-temperature, high-pressure gas discharged from an internal combustion engine is released directly into the atmosphere, it expands rapidly and makes a lot of noise, so a muffler, usually called a muffler, is inserted in the exhaust gas passage. to average the exhaust gas pressure changes,
It is released into the atmosphere as a smooth airflow. The above-mentioned muffler has a substantially cylindrical or rectangular muffler body equipped with a man-powered pipe and an output pipe for the exhaust gas, and further divides the inside of the muffler body into small chambers, through which the exhaust gas sequentially passes. By lowering the gas pressure and dissipating it to the outside as a nearly equal-pressure gas flow, it is possible to suppress the explosion noise of engines, etc. Additionally, a method of increasing the soundproofing effect by attaching a sound absorbing material to the inside of the muffler body is also used.

Problems to be Solved by the Invention However, in such conventional mufflers, the muffler body is constructed using metal materials such as M temporary or stainless steel, and these metal materials themselves have very poor sound absorbing effects. Therefore, there was a problem in that the sound absorption characteristics of the muffler itself were limited within a predetermined area. In other words, exhaust gas airflow noise can be thought of as noise inside the muffler, which is generated when the high-speed exhaust flow collides with the wall of the muffler body, and jet noise caused by expansion when it is released into the atmosphere from the muffler body. The above-mentioned noise inside the muffler is amplified by the collision of the exhaust flow with the metal and the resonance phenomenon at a specific frequency.

However, metals such as steel plates or stainless steel have very little sound absorption effect and do not have the effect of reducing resonance sound, so it is not possible to reduce the noise inside the muffler.

If glass wool or asbestos is attached inside the muffler body as a sound absorbing material, the resonance sound can be absorbed by the action of the sound absorbing material, but these glass wool, asbestos, etc. are emitted into the air and pollute the atmosphere. However, there is a problem in its use because it may become a source of pollution, such as harming the health of workers. Incidentally, since the steel plates and metals such as stainless steel are both heavy, there is also the drawback that the weight of the muffler body is also large.

Second, the present invention solves the problems that conventional silencers have, and provides a silencer that further improves the silencing effect by particularly reducing the noise inside the silencer. The purpose is to

Means for Solving the Problem: The exhaust gas generated from the internal combustion engine is passed sequentially from the input pipe to the output pipe of the muffler body, and a silencer is used to muffle the exhaust noise caused by the explosion of the internal combustion engine. The muffler body is molded using a heat-resistant epoxy resin obtained by adding one or more of a curing agent and an inorganic substance to an epoxy resin and subjecting it to a predetermined heat treatment to form a dense crosslink. .

Function The heat-resistant epoxy resin that makes up the muffler body changes from a glass region to a viscoelastic region to a rubber region at a certain high temperature, and at that time, the elastic modulus changes and it has the effect of absorbing noise at a specific frequency. brought about. The point of displacement to the viscoelastic region can be changed freely, and as a result, it becomes possible to reduce exhaust energy in any frequency band and absorb noise.

Examples Various examples of a silencer using a heat-resistant epoxy resin according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a basic embodiment of the present invention. In the figure, reference numeral 1 indicates a muffler body having a cylindrical or square tube shape, and an input pipe 2 and an output pipe 3 for exhaust gas are provided at both ends of the muffler body l. A mirror plate 4.5 is connected to the end plate 4.5. The muffler main body 1 and end plate 4.5 are molded using heat-resistant epoxy resin instead of conventional steel plate or stainless steel.

FIG. 2 shows a second embodiment of the present invention, in which the tip of the output pipe 3 connected to the end plate 5 is extended to the inside of the muffler body 1, and a collision plate 6 made of heat-resistant epoxy resin is fixed. It is. Therefore, after colliding with the collision plate 6 as shown by the arrow, the exhaust gas takes a detour and escapes into the atmosphere through the hole 3a of the output pipe 3.

FIG. 3 shows a third embodiment of the present invention, in which a partition wall 7 is provided in the muffler main body l, and a small chamber 8. The input pipe 2 connected to the end plate 4 is extended to the small chamber 9, and the output pipe 3 connected to the end plate 5 is extended to the small room 8. Further, the partition wall 7 is provided with a communication pipe 1O connecting the small chambers 8.9. In the case of this embodiment, the muffler body l, the mirror plate 4
, 5 as well as the input tube 2. A feature is that the output tube 3 and the communication tube 10 are all constructed using heat-resistant epoxy resin.

The method for producing the heat-resistant epoxy resin employed in the present invention will be described below.

The epoxy resin used as a base material in the present invention is a compound having at least two epoxy groups in one molecule, and typical examples include bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, etc. can be mentioned.

In the above base material, as a curing agent, an acid anhydride such as MIIA (methylnadic anhydride), an aliphatic, aromatic, or alicyclic amine compound such as triethylenetetramine, metaphenylenediamine, evomate, and its derivatives, After adding imidazole such as 2-ethyl-4-methylimidazole, a curing accelerator is added if necessary, and one or more inorganic substances selected from mica, silicon oxide, boron nitride, and talc are added. After the addition, it is poured into a mold, defoamed in a vacuum furnace, and then heat-treated. The heat treatment temperature varies depending on the type of curing agent, so it cannot be determined unconditionally.
For example, when the curing agent is an acid anhydride, the material is heated at about 120° C. for 2 hours, and then kept at about 200° C. for 4 to 8 hours for curing. In addition, when the curing agent is an aliphatic amine, it can be heated at about 30 to 50°C for 2 to 3 hours, maintained at a temperature of about 100°C for curing for 1 to 4 hours, and cooled. The adopted heat-resistant epoxy resin is obtained.

As shown in Table 1, the above-mentioned inorganic substances have the effect of improving the elastic modulus of the cured product and preventing deformation of the resin after molding.

Although the amount of the inorganic substance added cannot be determined unconditionally since it varies depending on the type and particle size of the inorganic substance, it is generally preferable to add at most 600 parts by weight per 100 parts by weight of the epoxy resin.

Further, the amount of the curing agent added is appropriately selected depending on the type of curing agent and the type of epoxy resin.

The action of a silencer using a bisphenol F type epoxy compound (trade name Epicote-80,7, manufactured by Shell Kagaku KK) as a base material and MNA as a curing agent will be described below. As shown in FIG. 4, the heat-resistant epoxy resin changes its dynamic viscoelasticity as the temperature rises, and in the illustrated example it is in the glass region up to 150°C.
When the temperature exceeds 150°C, it transitions to a viscoelastic region, and when it exceeds 180°C, it transitions to a rubber region. As described above, the change in the elastic modulus causes energy loss of the sound of a specific frequency that constitutes the noise, and a silencing effect occurs. The transition point from the glass region to the viscoelastic region can be changed by appropriately selecting the combination of the type of epoxy resin and the curing agent, or by changing the amount of the curing agent used. Furthermore, the transition point may be changed by adding a third component such as a reactive diluent or a flexibility imparting agent to the composition of the epoxy resin and curing agent.

Table 1 shows bisphenol F type epoxy resin (Epicor)
-807, manufactured by Shell Kagaku KK) with MNA and 2E4MZ (2-ethyl-4-methylimidazole) as a curing agent.
The results of measuring material properties with and without the addition of inorganic substances using the method are shown below.

Table 1 That is, it is clear that when the amount of the inorganic substance added is large, both the specific gravity 9 elastic modulus and the compressive strength show large values. The effect of 2E4MZ is not only as a curing agent, but also in improving the heat resistance of the cured product.

Table 2 shows the results of measuring the heat distortion temperature while varying the amount of 2E4MZ added.

Table 2 (Note) Curing conditions 120℃, 211+180℃, 6H Figure 5 shows bisphenol F type epoxy resin (Epicor) -
807, manufactured by Shell Chemical KK), bisphenol A type epoxy resin (Epicote-828, manufactured by Shell Chemical KK),
Evomate LX-IN and M are added as a curing agent to one or a mixture of two or more of various epoxy resins such as novolac type epoxy resin (Epicote-154, manufactured by Shell Kagaku KK).
A graph of changes in energy loss coefficient with respect to temperature when NA is added and mica is added as an inorganic substance is shown. That is, it is clear that the temperature dependence of the energy loss coefficient changes by changing the combination of epoxy resin and curing agent. In Fig. 5, (1) is Epicoat-807/! Bomate LX-IN = 100/35
゜(2) is shrimp:] -) -807/MNA/2E4
MZ=100/90/2.

(3) 4;t, x H:I-) -828/MNA
/2E4MZ=lGO/80/2.

(4) Fly Hi: J-To-154/MNA/2E4M
Z=lOO/10G/2.

A silencer was created using the heat-resistant epoxy resin obtained as described above, and an air-cooled single-cylinder 4-stroke gasoline engine (
Table 3 shows the results of measuring the noise at the silencer outlet using a sound level meter attached to the 250RQ x 67φ x 5631m. The muffler was made of Epicoat-807 and was prepared by adding Epomate LX-111 as a hardening agent at a ratio of LQQ:35. In Table 3, Not indicates a measurement example of a silencer according to the present invention, and NO2 indicates a measurement example of a silencer using a conventional steel plate.

Table 3 As is clear from Table 3, it is clear that the noise of the Not silencer is reduced compared to the conventional one, regardless of the engine speed. Father rated the engine above 3
．． When the silencer was inspected after operating at 8 PS and 4000 rpm for a long period of time, no abnormality was found in the exhaust system. Furthermore, since the specific gravity is 1.40 (7.8 for steel plate), an extremely lightweight silencer was obtained.

6 and 7 show the results of frequency analysis performed by recording the frequency at the exhaust pipe outlet of the engine via a pickup attached to the exhaust pipe outlet. In the diagram (A)
(B) is an example of a muffler using a heat-resistant epoxy resin according to the present invention, and FIG. 6 shows an example of a muffler made of a steel plate, and FIG.
The figure shows high load and high rotation (4000 rpm x 4.25 ps)
The case is shown below. In the example shown in Figure 6, there is almost no difference between (A) and (B) at each frequency, and the amplitude (
dB) depends on the shape of the muffler. However, as shown in FIG. 7, in the case of high load and high rotation, there is a considerable difference between the two, and (B) has a lower level at each frequency. This means that with a heat-resistant muffler, when the temperature of the engine exhaust gas becomes high, the temperature of the muffler rises, enters the viscoelastic region shown in Figure 4, changes the dynamic viscoelasticity, and increases the energy loss coefficient. Even if you use the same muffler as in the case of low load, as it changes and absorbs vibration,
This shows that the vibration of the exhaust pipe causes a change in air density, which reduces noise.

The heat-resistant epoxy resin employed in the present invention can be used in other types of motor silencers and marine engine silencers.

In addition to being able to be used as a muffler in gas turbine plants, it is also effective in aircraft applications due to its light weight.

Effects of the Invention As explained in detail above, the muffler using the heat-resistant epoxy resin according to the present invention has a muffler body constituting the muffler formed by adding a curing agent and one or more inorganic substances to the epoxy resin. Since the molding process was performed using a heat-resistant epoxy resin obtained by applying a predetermined heat treatment, the following effects can be obtained. That is, since the muffler body is manufactured using a heat-resistant epoxy resin that itself has a sound-absorbing effect, noise can be efficiently absorbed.

In particular, it is possible to absorb the airflow noise inside the muffler that is generated when the high-speed exhaust flow collides with the wall surface of the muffler body. Further, in the case of the present invention, since there is no need to use sound absorbing materials such as glass wool or asbestos, there is no dust dissipated into the air during use, and there is an advantage that no pollution is caused. Furthermore, since the muffler itself is extremely lightweight, it is advantageous when mounted on a car or the like, and also has the advantage of contributing to cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part showing a basic embodiment of a silencer using a heat-resistant epoxy resin according to the present invention, FIG. 2 is a cross-sectional view of a main part showing a second embodiment of the present invention, and FIG. 4 is a graph showing the transition state of dynamic viscoelasticity of the heat-resistant epoxy resin. FIG. 5 is a graph showing the change in the energy loss coefficient. 6 and 7 are graphs showing the relationship between vibration amplitude and frequency at the muffler outlet. l...Muffler body, 2...Input tube, 3...Output tube, 4.5...End plate, 6...Collision plate, 7...Partition wall, 8.9...Small chamber. Figure 1 Figure 2 Figure 3 Figure 4 □1 Relatives

Claims (3)

[Claims] (1) In a muffler that allows exhaust gas generated from an internal combustion engine to pass sequentially from an input pipe to an output pipe of a muffler main body to muffle exhaust noise caused by an explosion of the internal combustion engine, the muffler main body is made of epoxy resin. A heat-resistant epoxy resin, which is obtained by adding one or more types of curing agent and inorganic substance to a heat-resistant epoxy resin and subjecting it to a predetermined heat treatment to form a dense crosslink. Silencer using resin. (2) A silencer using a heat-resistant epoxy resin according to claim 1, wherein the curing agent is one or more of acid anhydrides, amine compounds and their derivatives, and imidazole. (3) The inorganic substance is a substance selected from mica, silicon oxide, boron nitride, and talc.
A silencer using the heat-resistant epoxy resin described in Section 1.